This proposal is comprised of two projects. The first project proposes a study of specific enzyme synthesis and expression during the cell cycle in synchronous plasmodia of the slime mold, Physarum polycephalum. Past investigations of enzyme synthesis in synchronous cells have relied almost exclusively on measurements of enzyme activities with the implied inference that appearance of these activites and the net concurrent syntheses of the respective enzymes are synonymous. Alternative expressions of gene regulation has been advanced by several laboratories to explain the three basic patterns which typify periodic appearance of enzymes activities during the cell cycle, namely: peak, step, and continous patterns. In the present application it is proposed that other regulatory processes involving enzyme turnover (synthesis and degradation) may account for these patterns, and that inferences made concerning gene regulation which are based on measurements of enzyme activities require more definitive demonstration that appearance of enzyme activities do indeed reflect new enzyme synthesis. We have proposed to study four enzymes which demonstrate the above activity patterns. They include: N-acetyl-8-D-hexosaminidase, uridine 5' -diphosphoglucose pyrophosphorylase, NAD ion-pyrophosphorylase, and thymidine kinase. Enzyme activity patterns will be correlated with their true respective synthesis patterns, the latter being constructed through the use of immunologic and radioisotope techniques as adjuncts to isolation and purification of each enzyme. On the basis of these results, control processes to account for the actual synthesis patterns will be investigated. The second project proposes a role for the polyamines, purtrescine, spermidine, and spermine, in the processes of mitosis or initiation of DNA synthesis. The effect of polyamine deficiency of these processes in intact plasmodia will be studied using an inhibitor of spermidine biosynthesis, methyl glyoxal bis(guanylhydrazone) (MGBG). An alternative investigation will attempt to isolate polyamine mutants from hapolid amoebae of a homothallic strain of Physarum. Homozygous, diploid plasmodial mutants derived from these amoebae will be used for identifying cell cycle events altered by polyamine deprivation.